/Engine/Source/Runtime/Engine/Classes/Engine/SkeletalMesh.h
Set the Versions of the geo and skinning data. We use those versions to answer to IsLODImportedDataBuildAvailable function.
void SetLODImportedDataVersions ( const int32 LODIndex, const ESkeletalMeshGeoImportVersions & InGeoImportVersion, const ESkeletalMeshSkinningImportVersions & InSkinningImportVersion )